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total sl-prokeys hits since April, 2003

On Thursday, August 21, 2003, at 2:45pm, my wife of 34 years, Rebecca, died in my arms in an emergency room.

The last words we spoke were in perfect synchronization: "I love you with all my heart."


Solid State Power Relay

One of the easier modifications ProKeys does to many Hammonds, is installing a power relay after the run switch.  The reasoning is that the run switch bears the electrical load of turning on not only the run motor, but also the AO28 preamp, reverb, power to the Leslies or Hammond Tone Cabinets, motors in the Leslies, lights, and any other peripheral equipment that may be connected to the Hammond or Leslies.

Our idea came after burning out a few original run switches, which are nearly impossible to find today.  The run switch, as well as the start switch, might still wear out mechanically, but we can extend its electrical life by using a power relay to carry the load.

The first step in this project is replacing the original incoming power wiring in the Hammond.  We use a much heavier gauge PVC jacketed wire, typically 14, and occasionally, 12 gauge.  We use blue and grey stranded wire, and twist them into a "harness".  These heavier wires are soldered directly to the lugs on the power strip, located on the tone generator, and are also connected to the power relay, mounted on the left side, near the start and run switches.  The grey side of the AC is wired as "common" for all devices, and the blue side is the side we switch.  This color code is maintained anywhere 110 volts is used. 

A little trick we use at ProKeys is to remove the bottom of the cover box which shields the power strip.  This provides space for all the power wiring to feed directly under it to the terminals.  A hacksaw, Dremel, or an air powered cutoff tool work perfectly. 

We wire the new relay in such a way that the run switch only turns on the relay, and nothing else.  The output of the relay is then wired to the "switched" power strip terminal on the generator, and from there, feeds anything which requires 110 volts when the organ is turned on.  The specific relay we've chosen to use is a very high quality device - CII (Continental Industries), solid state - rated at 10 amps.  It has screw terminals and a heat sink built into it.  Of course, it's somewhat costly and of course, we don't care.  With Hammonds, you save 50 cents over here, it costs you $100.00 over there.

On our own ProKeys Hammonds, we simplify the starting circuit by removing the 250 ohm dropping resistor on the generator power strip.  Along with the resistor, we also remove two of the wires that were part of the original harness going to the switches, as they're no longer needed.  The purpose of this resistor and its associated wires is to reduce the power going to the start motor only when both the start and the run switches are in the on position.  This is completely redundant, and we elected to remove this "feature" entirely. 

The "STOCK FREAKS" vehemently disapprove of this change, and we vehemently don't care.  It works perfectly for us, always did, and we'll keep it that way.

Note:  If you've read our page regarding the tone generator, you know that ProKeys generators will attain full rotation speed in 2-3 seconds.  Holding both switches "on for 8 seconds" to start a Hammond is simply ridiculous.  It's completely unnecessary, even in freezing conditions, and proves conclusively that the generator needs work to reduce the friction.

By modifying the wiring slightly, we now have only three wires going to the switches.  One carries half of the incoming 110 volts, and feeds one side of each switch.  The other two wires are returns from the switches.  The start switch return wire terminates on the generator power strip with the start motor, and the run switch return wire terminates on the power relay, to enable it.  Simplification with a smile.  Stock?  No.  Who cares?

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